1. Field of the Invention
The present invention relates in general to an ink-package assembly and a method of producing the same, and more particularly to techniques to minimize deterioration of deaeration (deairing) or degasification (degassing) of the ink-package assembly, and to prevent deformation of an ink package of the assembly due to its evacuation.
2. Discussion of Related Art
JP-A-11-129489 (FIG. 1, in particular) discloses an example of a known ink bag fluid-tightly containing or accommodating a mass of an ink used for an ink-jet recording apparatus. This ink bag has an opening in the form of a sleeve or hollow cylindrical member fixed thereto. An elastic sealing member or plug is fitted in this sleeve member, so that an interior of the ink bag is fluid-tightly isolated from an exterior space of the ink bag. The ink bag is accommodated within a cartridge casing such that the sleeve member is exposed through a side wall of the cartridge casing. In use of the ink bag, the cartridge casing is mounted on the ink-jet recording apparatus, such that the elastic sealing member fitted in the sleeve member is pierced with an ink-outlet needle provided on the ink-jet recording apparatus. The ink-jet recording apparatus has a recording head operable to deliver the ink from the ink bag onto a recording medium, through the ink-outlet needle and a supply conduit or tube connected to the needle.
The ink used for the ink-jet recording apparatus is manufactured by a process including a step of dissolving an ink material in a solvent, and a step of filtering a solution of the ink material. Where the ink as manufactured by this process is contained in the ink bag for use on the ink-jet recording apparatus, various kinds of gasses such as nitrogen, oxygen and carbon dioxide that are dissolved in the ink are introduced with the ink into the recording head, causing bubbles that may prevent the recording head from smoothly delivering droplets of the ink, giving rise to a risk of a poor recording performance of the recording head. To avoid this drawback, it has been practiced to effect a deaerating or degassing treatment of the ink, so as to reduce the amounts of the dissolved gases before the ink bag is filled with the ink. This deaerating treatment involves an operation to stir the ink within a pressure vessel at a reduced pressure (negative pressure).
When the ink bag fluid-tightly filled with the thus deaerated or degassed ink is transported, or stored for a long time before its use, oxygen and other gases in the air may be dissolved in the ink in the ink bag. JP-B2-3-61592 (column 4, lines 4–7, and FIG. 1, in particular) discloses a technique to prevent the dissolution of such gases in the ink. According to this technique, the ink bag filled with the degassed ink is accommodated in a suitable ink-bag casing, and this ink-bag casing is placed in a vacuum chamber the pressure of which is adjusted to a reduced pressure lower than the atmospheric level, and is fluid-tightly enclosed or accommodated within a sealing wrapper or container such as a plastic or rubber bag or a metallic can or box, so that the casing is kept under the reduced pressure in the evacuated sealing wrapper, during transportation or storage of the ink bag. The thus obtained assembly consisting of the ink bag, ink-bag casing and sealing wrapper will be referred to as an “ink-package assembly”. The ink bag and the ink-bag casing cooperate to constitute an ink package.
To prevent a poor recording performance of the ink-jet recording apparatus, the ink used for the recording apparatus is required to be kept in a highly deaerated or degassed state, as described above. The ink-package assembly according to the above-indicated technique disclosed in JP-B2-3-61592 permits the ink to be kept in a highly degassed state. Where a plurality of such ink-package assemblies each including a relatively small ink-bag casing are mounted on a carriage of the ink-jet recording apparatus, the ink-bag casing accommodated in the evacuated sealing wrapper more or less collapses due to the reduced pressure within the sealing wrapper. In this case where the walls of the relatively small ink-bag casing of each ink-package assembly has relatively small surface areas, the collapse of the ink-bag casing does not cause a significant problem during use of the ink-package assembly. Where the ink-bag casing has a considerably large volume or is a generally flattened structure, some of the walls of the ink-bag casing have relatively large surface areas, the ink-bag casing tends to be easily deformed under the reduced pressure within the sealing wrapper, causing problems such as difficulty or failure to mount the ink-package assembly on the recording apparatus, and a leakage flow of the ink from the ink-package assembly.